Electrical installation systems, such as, for example, conduit boxes, junction boxes, switch boxes, armored boxes, conduits, etc., are produced from a very wide range of materials, depending on the intended use. Materials used to date are steel sheet, aluminum, cast iron, (polyvinyl chloride (PVC), polyphenylene ether/polyphenylene oxide (PPE/PPO), polycarbonate (PC), polystyrene (PS), polypropylene (PP), polyethylene (PE), ABS or polyamide (PA). Depending on the field of use and national provisions, the electrical installation systems must meet certain requirements with respect to fire resistance, thermal stability, chemical stability, electrical properties, such as, for example, volume resistivity, dielectric strength or resistance to tracking, etc.
Thus, for example in Germany and Austria, the following values for flame retardance of electrical installation systems according to VDE 0471/DIN IEC 695 Part 2-1 are applicable: flame retardance for electrical installation systems for flush mounting and in concrete construction must be 650°, that for covers and lids must be 750° C., that for installation systems for mounting cavity walls must be 850° C. and that for terminals and semiflush-mounted conduit boxes for riser cables having 1.5 and 2.5 mm2 copper conductors must be 960° C.
The installation systems available nowadays and comprising PVC, PPE/PPO, PC, PC blend, PP blend, PA are self-extinguishing and non-flame-propagating according to ÖVE-EN 50086 or VDE 0605 in the event of a fire. Installation systems of steel sheet or aluminum must be protected with kneadable, intumescent cements or intumescent inlays to render said systems fire-retardant.
In the USA, the installation systems protected in this manner may not exceed the temperature of 181° C. in a fire test according to ASTM E-119.
However, in the case of fires, for example in the case of cable fires caused by short-circuits, serious consequences can nevertheless easily arise through the formation of dangerous fumes. Particularly in the case of installation systems whose flame retardance is due to a halogen, e.g. chlorine, fire results in the elimination of corrosive gases which can rapidly spread and cause permanent secondary fire damage. In order to avoid in particular the formation of corrosive gases, so-called HFT installation systems have been developed which are halogen-free, flame-retardant, i.e. self-extinguishing and non-dripping and thermally stable from −40° C. to +140° C. in the event of a fire. However, these systems, too, cannot prevent the spread of fumes.
For this reason, it was an object of the invention to provide electrical installation systems which prevent the spread of fumes in a simple manner.